The present invention relates generally to press apparatus for forming ends for metal cans, and more particularly, to an upstacking device used to remove ends from the press apparatus and place them into a stacked condition for packaging. Such apparatus is commonly used in converting previously formed shells into ends for self-opening cans and the like.
The production of metal can ends comprises a series of different operations, with a typical sequence described in U.S. Pat. No. 3,366,086. This patent discloses steps for initially creating the shell, and also describes scoring the opening in the shell, creating a pull tab, and making an integral rivet connection between the tab and the end. These latter three steps are often referred to collectively as conversion of the shells.
Certain presses, know as conversion presses, include tooling and related apparatus specifically adapted for carrying out this latter portion of the can end manufacturing process. One example of such a press is shown in U.S. Pat. No. 4,640,116. A typical conversion press includes a two-lane conveyor belt extending through the press and through in-line conversion tooling. Cooperating with the conveyor are downstacking and upstacking mechanisms located near but spaced from the slide. The downstacking mechanism provides unconverted shells which are received in circular apertures in the conveyor belt. The belt is moved stepwise through the press in synchronism with the opening and closing of the tooling. As a result of the press operation, an opening is scored in each shell, and a tab is formed and attached. After the converted ends move beyond the slide, the upstacking mechanism pushes the completed ends from the belt into a stack, from which the ends may be removed for further processing.
Occasionally, a defective end may be produced by the conversion press tooling. In such a case, it is necessary to temporarily halt the operation of the upstacker in order to prevent the defective end or ends from being placed into the stack of completed ends. However, such defective ends usually occur in isolated instances. Discontinuing of the upstacking operation is thus usually necessary only for one or several strokes of the press.
Accordingly, it is not efficient to stop the entire press to remove the defective ends. Rather, a better approach is to temporarily disable the upstacker mechanism so that the defective ends will continue along the conveyor belt to a later discharge position. After the defective ends have passed the upstacking mechanism, the mechanism can be re-engaged to continue the upstacking operation. One such engagement and disengagement means is disclosed in the above referenced U.S. Pat. No. 4,640,116.